A gigantic (can grow to a hundred feet in length), snake-like beast with a horselike head and a long snakelike body rising in humps out of the sea as it moves through the water; found in the Atlantic, Mediterranean, and Pacific Oceans. The sea serpent has received very bad Muggle press, in this case unjustified. Although many Muggle legends have grown up around sightings of the creatures, usually tales of horror and death, in reality sea serpents are harmless; there is no record of a sea serpent ever harming a human (FB).

The Sea Serpent of Cromer, Norfolk was killed by Glanmore Peakes (FW).

The favorite form of the Kelpie known as the Loch Ness Monster is that of a giant Sea Serpent (FB).